Isramart llc: Carbon emissions raise global temperatures, coastal risks

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In the last 100 years, global temperature has increased 1.3°F, and the pace of this increase in temperature is also accelerating. The year 2010 promises to be one of the hottest on record, according to the U.S. National Oceanic and Atmospheric Association (NOAA). The world’s surface temperature for January to June was the warmest on record.

It’s a good time to review what we know about global warming. Direct observations, thermometer records and satellites show that the air and oceans are warming, sea ice and glaciers are melting, and sea levels are rising globally. We also know longer-term climate records from tree rings as well as ice and sediment core samples. From these, we see that current warming is inconsistent with past natural cycles.

The primary cause of this warming is from humans. We burn fossil fuels that contribute to heat-trapping gases that thicken the greenhouse gas layer of our atmosphere. As this layer thickens, it traps more heat from the sun, which warms the Earth. This warming then leads to changes in our climate.

The human contribution to climate changes is the area where many in the public have the most doubt, so let’s address how we know that most of this warming is from human activities.

First, the long-term climate record, going back 650,000 years, shows natural cycles in Earth’s climate. It shows three cycles (or glacial periods), each lasting approximately 200,000 years. These cycles are based on well-understood variations in the earth’s orbit and show a relatively uniform and consistent pattern. These cycles oscillate between periods with low carbon dioxide concentrations and low temperature and periods with higher carbon dioxide concentrations and higher temperature.

Today, we are at the beginning of a period in this natural cycle of decreasing carbon dioxide and cooling. Yet carbon dioxide, the most prominent heat-trapping gas, is skyrocketing.

Today, we are pumping 30 million metric tons of carbon dioxide into the atmosphere every year. This increases by 2 percent a year, and doubles every 30 years. It’s not surprising that the concentration of CO2 in the atmosphere has increased by more than one-third since the industrial revolution (280 ppm to 390 ppm today). There is far more CO2 in the atmosphere today than at any point in the last 15 million years, and back then, the temperature was 5-10°F higher and sea levels were 75-100 feet higher.

Second, while changes in solar activity drive Earth’s climate, these data support the case for human-induced warming. Over the last hundred years, solar variations have been relatively small, and current trends would suggest a cooling in Earth’s climate. The small changes in solar variance are unable to account for the significant changes we see in our climate.

Third, the signatures or fingerprints in the atmosphere are unmistakably human. If the warming were only from long-term natural variation or solar activity, we would see consistent warming at all levels of our atmosphere. We don’t. When we look at the upper atmosphere, increasing solar energy should create a warming effect, but what we actually see is that part of our atmosphere cooling. This is consistent with the greenhouse effect, and suggests that human activities play a large role in the changes we are observing in our climate.

Fourth, there is a quickly growing record of observed climate changes by those in climate sensitive areas. Current climate impacts cannot be overstated because people in these communities have a long history of adapting to natural variations in climate. However, the difference today is that these changes are occurring much faster and in ways that these communities have never seen before.

People in the Arctic, small island nations, river deltas, and drying regions around the world have documented in very fundamental ways how their climate is changing. These communities all have in common a reliance on the environment for their daily survival.

And thus, for generations, the viability of their communities literally depended on the accuracy of climate information. So, their knowledge and direct observations of climate are critical to testing the accuracy of climate data and measurements. What we’ve found is that their observations of climate change impacts are consistent across extremely different geographic, social and cultural locations. These observations strongly support other climate measurements and data. In addition, understanding these climate change impacts help to illuminate what we can expect in the future in places like South Carolina.

Finally, short-term local weather variations are not necessarily always consistent with longer-term climate changes because climate is driven by different factors and based on long-term averages of weather. However, the weather experienced along the East Coast, for example, the major rain and snowstorms of recent months, is consistent with climate trends for the Eastern U.S. In general, climate change works at the extreme margins.

For the Eastern U.S., this means that we can expect to see more extreme ends of the temperature and precipitation, with more days say above 100°F (than in the past), and more precipitation and intense precipitation events. Indeed, the averages of temperature and precipitation will change, but it does so through the extremes. This is one of the most important aspects of climate change, because by changing those extremes, climate change increases risk and the challenge of adapting to those changes.

So here is what we know. The world is warming. Human activities are largely the cause. It is affecting us now. It will affect your children and grandchildren, and in much more intense ways. And we will experience it largely through extremes, which intensify the risks.

What the risks are, how they can be managed effectively and efficiently, and the specific challenges they present should now be the focus of our collective discussion.

P. Brian Fisher, Ph.D., is an assistant professor of poltical science and environmental studies at the College of Charleston.